I have been struggling for the past week with an issue with vpopmail
and quotas I could really use your expertise on. I have no problems
with the mailfilter other than people not getting messages when they
are over quota. I can tell you that if I delete the mailfilter and
.qmail file I do get bounces so I know it's maildrop and not vpopmail.

I have been using Matt Simersons mailfilter which is here:

http://goodcleanemail.com/files/other/mailfilter

I call it like so inside my users folder IE; ~vpopmail/domains/domain.xxx/user

|preline /usr/local/bin/maildrop mailfilter |  /usr/local/bin/setlock
/var/log/maildrop/setlock multilog t s1000000 n20 /var/log/maildrop

My problem is when I set a quota on any user the sender nor the
recepient do not get the warning about being over quota. If you look
at the mailfilter, here is the section that tells it to bounce:

to "|/var/qmail/bin/bouncesaying '$EXT@$HOST is over quota'"

Now when I look at the log when it's SUPPOSED to bounce, I get this:

and the users quota is:

quota:     1S
usage:     100%

2006-12-13 20:38:19.931378500 ====  BEGIN maildrop processing for
test@goodcleanemail.com ===
2006-12-13 20:38:19.967254500   message is clean
2006-12-13 20:38:19.969610500   quota enabled delivery to
/usr/home/vpopmail/domains/goodcleanemail.com/test/Maildir
2006-12-13 20:38:20.026902500   BOUNCED: bouncesaying
'test@goodcleanemail.com is over quota'
2006-12-13 20:38:20.048024500 Date: Wed Dec 13 20:38:20 2006
2006-12-13 20:38:20.048028500 From: "William Olson" <wolson@gmail.com>
2006-12-13 20:38:20.048030500 Subj: test
2006-12-13 20:38:20.048031500 !Err: |/var/qmail/bin/bouncesaying
'test@goodcleanemail.com is over quo (2284)
2006-12-13 20:38:20.048032500

Now I have looked EVERYWHERE for a fix and below are some of the ones
that look promising but nothing wants to work

http://www.courier-mta.org/imap/?README.maildirquota.html
Just seems to be a manual page

http://archive.netbsd.se/?ml=courier-maildrop&a=2004-12&m=517844
This page recommends using a wrapper but nope, not working there either

http://www.howtoforge.com/forums/showthread.php?p=49889
Tried the script ColdDot posted, nothing happened there

http://copilotconsulting.com/mail-archives/courier.2006/msg02037.html

So at this point after googling this since last friday and trying to
find a solution and I am at a loss. I know bouncing messages to
senders isin't a good idea as spammers spoof email addresses. I dont
know if theres a way to send a over quota mesage to both the sender
and recepient or just make it an option to send to one or the other.

As of today I am making a bit of progress. I have changed 2 lines in my mailfilter like so

XBOUNCE="| bouncesaying '$EXT@$HOST is over quota'"

and the next line is what is used to look like

to "| bouncesaying '$EXT@$HOST is over quota'"

So now in my maildrop logs I am seeing

2006-12-14 08:27:43.160942500 ====  BEGIN maildrop processing for test@goodcleanemail.com ===
2006-12-14 08:27:43.172333500   message is clean
2006-12-14 08:27:43.174365500   quota enabled delivery to /usr/home/vpopmail/domains/goodcleanemail.com/test/Maildir
2006-12-14 08:27:43.178787500   BOUNCED: bouncesaying 'test@goodcleanemail.com is over quota'
2006-12-14 08:27:43.178825500 === END === success

but I never get a bounce!